Allow fetch callback to alter url

[blahgeek]

So that the server may return response especially for InstantClick (e.g. strip header/scripts to reduce bandwidth). Also this could be useful for requesting contents from CDN in a different domain without affecting real location in address bar.

[dieulot]

What I planned is sending an X-InstantClick HTTP header to be able for the server to identify whether the request is from InstantClick or not.

Your solution is interesting though because it would allow to strip headers for static sites too, and helps to avoid the possibility of shooting oneself in the foot with caching.

I’ll think about it more thorougly and see if it’s an easier solution or not. Thanks!